The present invention relates generally to optical systems that monitor oxygen levels in tissue. More specifically, the present invention relates to an optical probe that includes light sources, detectors, and a marking apparatus for marking local tissue regions that are probed by the optical probe.
Oximeters are medical devices used to measure oxygen saturation of tissue in humans and living things for various purposes. For example, oximeters are used for medical and diagnostic purposes in hospitals and other medical facilities (e.g., surgery, patient monitoring, or ambulance or other mobile monitoring, such as for hypoxia); sports and athletics purposes at a sports arena (e.g., professional athlete monitoring); personal or at-home monitoring of individuals (e.g., general health monitoring, or personal training, such as for a marathon); and veterinary purposes (e.g., animal monitoring).
In particular, assessing a patient's oxygenation state is important as it is an indicator of the state of the patient's health. Thus, oximeters are often used in clinical settings, such as during surgery and recovery, where it may be suspected that the patient's tissue oxygenation state is unstable. For example, in reconstruction surgeries, it is desirable to distinguish between tissue that is viable and non-viable to save as much viable tissue as possible. Via the use of oximeters, physicians can attempt to distinguish between viable and non-viable tissue. However, physicians typically have to remember a map of viable tissue and non-viable tissue, which may slow down medical procedures.
Pulse oximeters and tissue oximeters are two types of oximeters that operate on different principles. A pulse oximeter requires a pulse in order to function. A pulse oximeter typically measures the absorbance of light due to pulsing arterial blood. In contrast, a tissue oximeter does not require a pulse in order to function, and can be used to make oxygen saturation measurements of a tissue flap that has been disconnected from a blood supply.
Human tissue, as an example, includes a variety of molecules that can interact with light via scattering or absorption (e.g., via light-absorbing chromophores). Such chromophores include oxygenated and deoxygenated hemoglobins, melanin, water, lipid, and cytochrome. Oxygenated and deoxygenated hemoglobins are the most dominant chromophores in the spectrum range of 600 nanometers to 900 nanometers. Light absorption differs significantly for oxygenated and deoxygenated hemoglobins at certain wavelengths of light. Tissue oximeters can measure oxygen levels in human tissue by exploiting these light-absorption differences.
Despite the success of existing oximeters, there is a continuing desire to improve oximeters by, for example, improving measurement accuracy; reducing measurement time; lowering cost; reducing size, weight, or form factor; reducing power consumption; and for other reasons, and any combination of these.
Therefore, there is a need for oximeters that have improved form factors and that relieve physicians and medical personal of having to remember of map of tissue scanned by an oximeter.